Previous work by the applicants has established the presence of tissue-type specific immunity in patients with malignant tumors of various histological types including gliomas. A class of human natural killer cells has been isolated and identified from human peripheral blood. There is a controversy concerning the interaction of natural and tumor-specific immunity in microcytotoxicity assays, and we propose to address ourselves to the problem with the following specific aims: a) Natural immunity to human neoplasms: 1. to isolate and characterize "natural killer cells" (NK cells) from human peripheral blood, 2. to study the interaction of natural and tumor-specific immunity in microcytotoxicity assays with characterized effector cell populations, 3. to investigate whether high and low incidence of neoplastic disease in Finnish families correlates with high and low NK cell activity in vitro. b) Immunity to normal tissue-specific antigens in neoplastic diseases: 1. to further study the role of glia-specific antigens in the immunological reactions to human gliomas, 2. to develop diagnostic methods for gliomas based on these reactions. 3. To isolate and characterize tumor-specific antigens from human gliomas. 4. To investigate the possibilities of manipulating the immunological reactions of laboratory animals to glia- and glioma antigens.